We attempted to clone our production database to our development environment using RMAN, following a process successfully used on multiple occasions in the past.

Both databases are running on UNIX and are versoin 11.2.0.2.7 (with JUL2012 PSU applied).

The RMAN cloning operation completed WITHOUT errors AND, the new database can be shutdown, started, and accessed via SYS logoin, but all attempts by users to access the databsae returns "corrupt datafile" message on most datafiles.

Yes, but the UNDO tablespace is just one of many --- in fact, most tablespaces are affected, including the SYSTEM tablespace.

Following one clone attempt, we were able to manually correct a large portion of the corruption errors and make the instance accessible, but any attempt to access indexes and/or modify data, resulted in corruption messages.